An essential problem in optimizing a telecommunications network is balancing equipment and trunking against service and cost. Network design involves predicting future demand based on past results, evaluating the capacity of equipment and facilities, and providing the correct amount of capacity in the proper configuration, in time to meet service objectives. Since virtually every element of a telecommunications system is subject to failure or overload effective testing, monitoring, control, and maintenance is essential to obtain an acceptable level of performance.
U.S. Pat. No. 5,475,732 issued to Eugene Pester Dec. 12, 1995, for Common Channeling Signaling Network Maintenance and Testing, describes an SS7 Network Preventative Maintenance System for detecting potential SS7 and switched network troubles, automatically analyzing the troubles, and providing alarm and corrective action to avoid major network events. The Pester SS7 Real Time Monitor System described in that patent is a multi stage SS7 network preventative maintenance tool that detects potential SS7 and switched network troubles, automatically analyzes those troubles, and provides alarm and corrective action instructions to maintenance personnel in time to avoid a major network event. This is accomplished by placing real time SS7 monitors on links at the Signal Transfer Points (STPs).
Information on exceeded Link Load, exceeded Message Signaling Unit (MSU) frequency and Network Management status/error conditions is passed to a Stage 1 controller or process. The Stage 1 process controls link monitors capable of monitoring upwards of 32 link monitors at a single STP. The monitors perform preliminary link analysis on error conditions. If the monitors identify trouble on any of the links, alarm information is sent to a Stage 2 controller or process via the Stage 1 process. The Stage 2 process controls all Stage 1 and associated monitors from an STP pair. If Stage 2 determines that there is an STP pair network trouble, it generates alarm and corrective action information and passes it to the Stage 3 controller or process. The Stage 3 process controls all Stage 2 controllers or processes in the operating company. If Stage 3 determines that there is potential or real company network trouble, it generates alarm and corrective action information and display signals on maintenance terminals in the company's SS7 control center (SEAC, SCC, etc.). Stage 3 also alerts the Stage 4 controller process.
U.S. Pat. No. 5,592,530 issued to Brockman et al (Brockman) on Jan. 7, 1997 for Telephone Switch Dual Monitors, relates to testing and monitoring systems for evaluating the operations of telephone switches and more particularly to monitoring systems which are arranged to capture data between nodes of a telephone switching system where the data flows between mated nodes, as in an SS7 common channel signaling network. The Brockman Patent uses the term “telephone switches” to refer to service transfer points (STPs) in the SS7 network.
The patent indicates that an SS7 network can be thought of as a separate switching system which is used prior to, during, and at the end of calls for the purpose of routing control information. Whenever two switches or elements in the SS7 network have to pass call control information to one another during or prior to a phone call, they pass this data via the SS7 network. The patent describes an SS7 network as traditionally having three basic types of network node elements. These are listed as the Service Switching Point (SSP), which may be a central office, tandem or end office switch, a Service Control Point (SCP), and a Signal Transfer Point (STP), which is described as essentially a packet switch which routes the messages from SSPs and SCPs to SSPs and SCPs.
The SS7 network is stated to be critical to operation of the telephone network and to require the deployment of “surveillance equipment to monitor the links connecting the nodes of the SS7 network.” The patent describes the topology of the SS7 network as such that STPs are deployed in a mated pair configuration at geographically separate locations. A set of SSPs and SCPs will be connected to a mated pair of STPs. This conglomeration of SSPs, SCPs, and mated pair STPs is called a cluster. Clusters are then connected by D-QUAD links between STP mated pairs.
The patent indicates that it is often the case that the messages going from switch A to switch B travel one route on the network, while the messages going from switch B to switch A travel a different route. The network surveillance equipment that monitors the link is designed to capture and correlate as much signaling information as possible regarding network activity. Because of the different paths that messages may take, data relating to a subscribers phone number may be all in one STP, or split partially in one STP and partially in the other STP of the mated pair “which may be in a different city.”
The patent postulates that what is needed is a “distributed state machine that can capture all of the SS7 messages within a mated pair cluster and correlate the fragmented SS7 messages pertaining to a particular call or transaction to a single data record.” The patent further states that what is needed is a filtering of redundant or unnecessary SS7 messages in order to compile call transaction records containing a minimum amount of essential data in order to evaluate overall system performance and to diagnose system errors when they occur.
The patent indicates that “the ability to capture all of the SS7 messages within a mated pair cluster and correlate the fragmented SS7 messages makes other improvements to telephone network services possible. In addition to the performance monitoring applications outlined above, there is a need for systems which are capable of generating call detail records from the SS7 messages of a mated pair cluster for use in billing systems and to implement a fraud detection system for certain types of telephone calling cards.” The patent goes on to indicate a need for telephone monitoring systems which enable a user to implement a call trace mechanism that can track all SS7 messages associated with a particular phone number in order to retroactively trace harassing or obscene phone calls.
Additionally, it is stated that there is a need for a telephone monitoring system which can monitor the SS7 messages of a mated pair cluster in order to implement what is called “mass call onset detection.” This is stated to be useful in circumstances where a large number of callers attempt to call a single phone number at the same time, such as where radio stations give away prizes to callers who call in immediately, thereby creating a mass call-in. It is indicated that mass call onset detection applications detect the situation early as the number of SS7 messages pertaining to a particular phone number increases rapidly and alerts the phone company quickly to the large number of busy conditions associated with a given phone number.
In summarizing its description the patent states that the monitoring devices “key off the links to the SS7 itself, so that all data on the SS7 circuits entering the STPs are monitored.” However, a level of filtering is provided to capture only the data which is necessary for providing call detail records. The STP is stated to be the central routing point for the SS7 data. Monitoring devices are connected by a communication link that enables the monitoring devices to track and correlate all the SS7 data at an application layer in a distributed fashion across two STPs. From this one can determine error conditions at the application layer of the network. It is also possible to generate information that could be used for fraud detection and could generate another level of call detail records.
While the above discussed Pester and Brockman et al patents describe the usefulness of monitors in an SS7 common channel interoffice signaling network for event detection, neither of these patents is directed to the particular problems addressed by the present invention. The Pester patent places emphasis on monitoring of the SS7 network itself in order to detect troubles in its functioning. SS7 link monitors are utilized on each SS7 link in the illustrated depiction of that system. The Brockman et al patent focuses on monitoring of all links to the STPs in a pair and the assembly of related SS7 signaling messages comprising a record of call completions.
While these methodologies may be effective for their stated purposes there remains a distinct need for an efficient and effective tool for coping with the types of traffic and billing problems which are presently associated with overload of trunk circuits to Internet Service Providers (ISPs) and to Competitor Local Exchange Carriers (CLECs). Attempts to use other more traditional approaches, such as the switches themselves and the Engineering Data Acquisition System (EDAS), fell short of providing the desired information.
It is accordingly an object of this invention to provide a relatively low cost solution to those problems. While two specific problem situations are mentioned as typical for ease of description of the invention, it is to be understood that those problems are to be regarded as examples only, as the invention is applicable to a wide variety of related problems.
It is another object of the invention to provide a timely, powerful, cost effective means of analyzing traffic on the Public Switched Telephone Network (PSTN).
It is a further object of the invention to provide a flexible, expedient, accurate, and cost effective method to identify individual high usage lines contributing to network blockage.
It is another object of the invention to provide a tandem trunk planning resource which will accommodate future tandem switch growth respondent to customer calling patterns, communities of interest and points of origin and destination.
It is yet another object of the invention to implement Internet Service Provider (ISP) studies and enable better service to ISP customers while maintaining optimal network utilization.